A comparative study of the iron-clearing properties of desferrithiocin analogues with desferrioxamine B in a Cebus monkey model

A comparative study of the iron-clearing properties of subcutaneously administered desferrioxamine B (DFO) with those of orally administered desferrithiocin sodium salt (1), desmethyl desferrithiocin (2), desazadesmethyl desferrithiocin sodium salt (3), desazadesmethyl desferrithiocin pivaloyloxymethyl ester (4), and desazadesmethyl-5,5- dimethyl desferrithiocin (5) in an iron-loaded Cebus monkey model and a non-iron overloaded bile duct-cannulated rat model is presented. All six drugs, which performed well in rodent studies, demonstrated increased efficiency in the Cebus monkey model. When administered to rodents at a daily dosage of 384 mumol/kg over a period of 10 days, drug 1 demonstrated severe renal toxicity. whereas drugs 3, 4, and 5 exhibited severe gastrointestinal (GI) toxicity. Under the same experimental protocol, drug 2 did not show significant toxic side effects. In addition, to further evaluate the iron-clearing properties of analogue 2, a dose-response study was performed in the primates that showed that iron excretion increased in a dose-dependent fashion.     

Orientation and specificity of fibrin protofibril binding to ADP- stimulated platelets

We have investigated the molecular basis of platelet:fibrin binding by studying interactions between platelets and protofibrils, soluble two- stranded polymers of fibrin, which are intermediates on the fibrin assembly pathway. The specificity of these interactions was examined with transmission electron microscopy (TEM), which clearly showed thin fibers with lengths to 150 nm attached to the cell surface of normal, stimulated platelets. Immunogold electron microscopy using rabbit anti- human fibrinogen as the first stage antibody verified the identity of the surface-bound molecules, and the immunogold distribution paralleled that observed with the fibrin/fibrinogen molecules alone. Contacts between the ends of the fibers and the platelets were frequently observed, but lateral contacts were also evident. Given the diameter at the point of fibrin contact (18.2 +/- 1.3 nm), it is possible that several glycoprotein receptors were involved in binding each protofibril. Morphometric analyses demonstrated that normal platelets stimulated by ADP in the absence of exogenous fibrin(ogen) or in the presence of fibrin protofibrils and antibodies directed against the GPIIb/IIIa complex lacked this molecular layer on the surface. Neither protofibrils nor fibrin fibers adhered to the surface of Glanzmann's thrombasthenic platelets, as demonstrated by TEM and microfluorimetry. Synthetic peptides of sequence RGDS and HHLGGAKQAGDV effectively blocked the binding of protofibrils to the surface of normal, stimulated platelets while synthetic GHRP had no effect. These results provide direct evidence for multiple points of attachment between fibrin protofibrils and the glycoprotein IIb/IIIa complexes present in a functional conformation on the surface of normal, stimulated platelets.     

Regulatory mechanisms in cell-mediated immune responses. VI. Interaction of H-2 and non-H-2 genes in elaboration of mixed leukocyte reaction suppressor factor

Previous studies have shown that alloantigen-activated spleen T cells produce a soluble factor which suppresses mixed lymphocyte reaction proliferative responses, and that the interaction between suppressor and responder cells is controlled by genes of the H-2 complex. However a defect in the expression of suppressor activity was identified in the mouse strain C57BL/6J. Factor prepared from alloactivated B6 spleen cells failed to suppress MLR responses of syngeneic or H-2 compatible responder cells. Unimpaired suppressor factor production by other H-2 (b) strains and failure of suppressor factor production by a B6 congenic strain, B6.C-H-2(d) isolated the defective gene to the non-H-2 portion of the genome. In addition, the defect appeared to be related specifically to inability to produce an active factor, while the capacity to respond to suppressor molecules was unimpaired. The genetic character of the non-H-2 gene action was identified in F1 hybrid studies. Initially F(1) hybrids of the nondefective histoincompatible strains were studied. Suppressor factor from F1 cells suppressed the responses of both parental strains, and parental factors each suppressed the response of F(1) cells. Adsorption of F(1) factor with Con A-activated thymocytes of either parental strain removed suppressor activity specific for that strain, leaving activity against the other parental strain intact. The data support cedominant expression and production of distinct, parental H-2 haplotype-specific suppressor molecules by F(1) suppressor cells. An F(1) hybrid of the defective B6 strain with nondefective BALB/c produced suppressor factor which was also capable of suppressing both parental strains. Production of a suppressive B6-reactive factor by F(1) cells was verified by adsorption studies. Thus it appears that non-H-2 genes of the BALB/c parent acted in a genetically dominant fashion to provide the function required for expression of B6 suppressor molecules. We conclude that multiple genes control the expression of alloactivated suppressor cell activity, with at least one gene mapped to the I-C subregion of the murine major histocompatibility complex and one or more genes mapped to the non-H-2 gene complement.     

Familial dysbetalipoproteinemia associated with apolipoprotein E3-Leiden in an extended multigeneration pedigree.

By the careful screening of familial dysbetalipoproteinemic (FD) patients, five probands showing heterozygosity for the APOE*3-Leiden allele were found. Genealogical studies revealed that these probands share common ancestry in the 17th century. In a group of 128 family members, spanning three generations, 37 additional heterozygous APOE*3-Leiden gene carriers were detected. Although with a variable degree of severity, all carriers exhibited characteristics of FD such as (a) elevated levels of cholesterol in the very low density lipoprotein (VLDL) and intermediate density lipoprotein (IDL) fractions, (b) elevated ratios of cholesterol levels in these density fractions over total plasma levels of triglycerides, and (c) strongly increased plasma levels of apolipoprotein E (apoE). Multiple linear regression analysis revealed that most of the variability in expression of FD in APOE*3-Leiden allele carriers can be explained by age. Body mass index showed a less significant influence on the expression of FD. Gender had no effect on the expression in E*3-Leiden allele carriers, nor did it influence the age of onset of FD. In the group of APOE*3-Leiden allele carriers, we found that the E*2 allele enhances the expression of FD, whereas the E*4 allele had the opposite effect. Isoelectric focusing of plasma and of isolated VLDL, IDL, and high density lipoprotein density fractions showed that in E*3-Leiden allele carriers the apoE3-Leiden variant largely predominates over its normal apoE counterpart, especially in the VLDL and IDL density fractions. We conclude that in APOE*3-Leiden allele carriers FD is dominantly inherited with a high rate of penetrance, i.e., the presence of normally functioning apoE molecules in the plasma does not prevent the age-related expression of this disease.     

Fatal outcome in a patient with autoimmune hemolytic anemia associated with an IgM bithermic anti-ITP

BACKGROUND: Several cold autoantibodies (usually IgG) with IT specificity have been reported previously, as have autoantibodies with joint I and P blood group specificities (IP1, ITP1, iP1, IP). A fatal outcome associated with an IgM cold autoantibody of ITP specificity is reported. CASE REPORT: A 54-year-old man suffered from progressively severe cold autoimmune hemolytic anemia for 9 months. Hemoglobin concentration ranged from 6 to 7 g per dL (60-70 g/L) and reticulocytes from 3 to 5 percent (0.030-0.050). The direct antiglobulin test was weakly positive for IgM and strongly positive for C3d. The serum contained a cold agglutinin that reacted strongest with cord i red cells (RBCs) > adult I RBCs > adult i RBCs, which is consistent with IT specificity. The Donath-Landsteiner test was positive; the reaction was neutralized by globoside. The serum reacted weakly or was negative with RBCs from five group p blood donors, which suggests anti-ITP specificity. Dithiothreitol treatment of the serum abolished the cold agglutinin reactivity, which suggests that the anti-IT was IgM. The patient received > 40 RBC transfusions and failed to respond to oral steroids, oral cytoxan, high-dose pulse intravenous steroids, and plasma exchange at room temperature and at 35 degrees C. He died of sepsis following an unsuccessful trial of chlorambucil. Autopsy revealed unsuspected disseminated non-Hodgkin's lymphoma. CONCLUSION: Serologic studies are consistent with our patient's having a single IgM cold autoantibody with IT and P specificities (anti-ITP) and requiring both specificities on the same RBC to permit maximal antibody expression.     

Genome-wide linkage scan for atypical nevi in p16-Leiden melanoma families

In most Dutch melanoma families, a founder deletion in the melanoma susceptibility gene CDKN2A (which encodes p16) is present. This founder deletion (p16-Leiden) accounts for a significant proportion of the increased melanoma risk. However, it does not account for the Atypical Nevus (AN) phenotype that segregates in both p16-Leiden carriers and non-carriers. The AN-affected p16-Leiden family members are therefore a unique valuable resource for unraveling the genetic etiology of the AN phenotype, which is considered both a risk factor and a precursor lesion for melanoma. In this study, we performed a genome-wide scan for linkage in four p16-Leiden melanoma pedigrees, classifying family members with five or more AN as affected. The strongest evidence for an atypical nevus susceptibility gene was mapped to chromosome band 7q21.3 (two-point LOD score=2.751), a region containing candidate gene CDK6.